Sputum color as a marker of acute bacterial exacerbations of chronic obstructive pulmonary disease

SummaryWe analyzed 795 sputa from 315 patients (233 males, mean age 69.3±8.8 years, mean number of exacerbations 2.52/patient) with acute exacerbations of moderate-to-severe chronic obstructive pulmonary disease (COPD) (mean steady-state FEV1 42.5±7.8% of predicted). 581/795 sputa were considered adequate. Sputum was analyzed by a quali-quantitative colorimetric scale allowing both color distinction and color degree of intensity. Quantitative culture was then performed (threshold: >106CFU/mL). Samples were distinguished in mucoid (145) and purulent (436) sputa. Absence of bacterial growth was observed in 22% and 5% of mucoid and purulent sputa, respectively. Among mucoid sputa, Gram positive bacterial growth occurred more commonly compared to Gram negative and Pseudomonas aeruginosa/Enterobacteriaceae (56%, 24%, 20%, respectively). In purulent sputa, Gram positives were found in 38% of cases, Gram negatives in 38%, and P. aeruginosa/Enterobacteriaceae in 24%. We evaluated whether functional impairment (FEV1) orientates as to the infectious etiology of exacerbations. Significant differences were observed in the distribution of pathogens. Gram negative and P. aeruginosa/Enterobacteriaceae were isolated more frequently in the sputum when FEV1 was